3-d printed insert to fit standard aerogarden pod in a mason jar top. This helps keep light out, moisture in, and cuts down on any algae growth. I love to grow milkweed in these- caterpillars are much safer climbing around these (caution-tiny ones may find a way to squeeze past the fitting) these fit nicely in caterpillar habitats. If you look closely, the first photo is one plant cut in two look at the roots(also, i learned to cover the jar so algae growth is less).